1. Field of the Invention
The present invention relates, in general, to a poly(trimethylene terephthalate) (PTT) BCF carpet modified cross-section yarn and a method for preparing the same and in particular, to a poly(trimethylene terephthalate) BCF carpet modified cross-section yarn and a method for preparing the same, in which a Y-shaped nozzle having a properly controlled modification ratio, an arm angle, and a length ratio of arms is used. The poly(trimethylene terephthalate) BCF carpet modified cross-section yarn according to the present invention has uniform physical properties, and excellent bulk property and spinning efficiency.
2. Description of the Prior Art
Generally, a synthetic fiber material of BCF (bulked continuous filament) for use in carpets is selected from the group consisting of nylon, polypropylene, and poly(ethylene terephthalate). To produce a carpet having excellent luster, a degree of cover, the sense of touch, and stain-resistance, filaments with various shapes of a cross section have been developed. Most of the filaments with non-circular cross sections which have been developed for application for carpets are made from polyamide, but the cross sectional non-circularity does not allow the application of poly(trimethylene terephthalate) for carpets owing to its very low tenacity.
For example, Korean Patent No. 25283 discloses a method for preparing polyamide modified cross-section yarn with a Y-shaped cross-section, in which non-circular cross-section yarns with an uniform cross sectional area can be produced during cooling by non-uniformly varying hole sizes of a spinneret relative to each other. However, with respect to moving velocity of yarns, an amount of cooling air, and a cooling temperature in a cooling zone, cross sectional areas of filaments are not substantially varied but filaments have non-uniform shape of cross sections, thereby a postprocess efficiency is lowered—capillaries are readily formed and cutting efficiency is reduced during the tufting.
Furthermore, Korean Patent No. 27228 discloses carpet synthetic filaments with a triangular cross-section, in which a ratio of an arm angle to a modification ratio is too large, and so a synthetic filament has a triangular cross-section. Therefore, the synthetic filaments have a low bulk property because the modification ratio is low. Also, a polyamide modified cross-section yarn with a Y-shaped cross section has excellent bulk property within a range of high modification ratio, but poly(trimethylene terephthalate) with a low tenacity and a Y-shaped cross section can hardly endure a friction between a spinning guide and poly(trimethylene terephthalate), and so spinning efficiency is rapidly reduced. Accordingly, this invention is restricted to polyamide.
A carpet for home or office uses particularly requires stain-resistance. A carpet made from poly(trimethylene terephthalate) filaments has excellent resilience, stain-resistance, and dyeing property to disperse dyes. Also, the carpet has excellent elastic recovery and pile height retention in comparison with poly(ethylene terephthalate) or poly(butylene terephthalate). Therefore, poly(trimethylene terephthalate) has lately attracted considerable attention as new material for carpet production.
U.S. Pat. No. 5,662,980 discloses carpets made from poly(trimethylene terephthalate) bulked continuous filament modified cross-section yarn, in which poly(trimethylene terephthalate) BCF yarn used to make carpets has excellent stain-resistance, bending ability, and pile height retention. However, this invention has disadvantages in that elastic recovery of the carpet is lowered because bulk property of a grey yarn is reduced owing to a low modification ratio of 1.7, and dyeing property of the carpet having a structure of a cut pile is reduced, and also appearance of the carpet is poor because apparent specific gravity is low.